Reduction gear device



4D. R. DE TAR REDUCTION GEAR DEVICE April 13, 1937.1.

Filled Feb. 2:3,A 19:54

Patented Apr. 13, 1937 f PATENT oFFlcE REDUCTION GEAR DEVICE Donald B..De Tar, Audubon, N. J., aitnor to Radio Corporation of America, acorporation of Delaware Application February 28, 1934, Serial No.113,368

3` Claiml.

Other objects and advantages will hereinafter' l5 appear For the purposeof illustrating my invention, an embodiment thereof is shown in thedrawing,

wherein Figure l is a front elevationalv view, partly in' section,showing my improved device applied to a tuning condenser, the sectionbeing taken on the line l-I in Fig. 2;

Fig. 2v is an enlarged, fragmentary, sectional gew, the section beingtaken on the line 2--2 in s. 1:

) Fig. 3 is a fragmentary, sectional view, the

section being taken on the line 3-3 in Fig. 2; and Fig. 4 is afragmentary, sectional view, similar to Fig. 2, showing a modification.

As shown more clearly in Fig. 2, my improved device comprises a U-shapesupporting member Iii secured by screws i2 to the front plate n4 of avariable capacitor or tuning condenser IB in a radio receiver. A spoolI8 is fixed on a shaft I, 20 which is journaled in the spaced, parallelsides 22 and 24 of the member i0. i

Complementary rotor elements, in the' form of balls 28, are supportedbetween the ends 28A of the spool, and on the same side of the axis ofrotation of the latter in line, parallel to the axis.

The supporting means for the balls 28 is in the form of a U-shaperetainer member 30 fixed to the member i0 by rivets 32, and provided inthe U with circular holes 34 in which the balls 28 have a free runningfit. A tongue 36 extending outwardly from the free end of the member 30fits snugly in a notch 38 in the member i0, whereby this end of theretainer 30 is fixed against relative movement with respect to themember 4i 0.

As shown more clearly in Fig. 3, the bottom of the member 80 is cut awayat 40 to accommodate the spool i8.

In applying my improved device to the condenser, the edge of a disc 42,fixed on the con- (Cl. 'i4-L16) denser shaft 44, is inserted between theballs 28. ,The distance between the spool ends 28 is made slightly lessthan twice the diameter of one of the balls 26, plus the thickness ofthe disc 42, so that insertion of the edge of the disc 42 between theballs 26 must be forced, whereupon the spool 5 ends 28, which are madeof spring material, are flexed slightly outwardly. With the partsassembled, therefore, the balls 26 are held in frictional drivingengagement with the opposite faces of the disc 42 and the frictionaldriving surfaces of the spool ends 28 by the'spring action of thelatter.'

In making an adjustment, the shaft 20 is rotated by a knob 48 fixedthereon. Due to the frictional driving engagement between the innervfaces of the spool ends 28 and the balls 26, the latter are then causedto rotate about xed axes each perpendicular to the axis of rotation ofthe spool, the free running fit of the balls in the retainer permittingthis. The rotor plates of the condenser i8 are then caused to rotate byreason of the frictional driving engagement between the balls and therespective opposite faces of the disc 42. The relation between the anglethrough which the condenserplates are rotated 25 and the angle throughwhich thev shaft 28 is rotated is equal to the relation between thedistance from the axis of shaft 20 to the point of contact of the balls28 with the disc 42, and the distance from this point to the exis of theshaft 30 44. From this it will be seen that a substantial reduction isobtained, so that very fine adjustl ments of the condenser i6 can bemade by turning the knob 48 through a small angle. As represented in thedrawing. there is a reduction of 35 about ten to one between the shafts28 and 44.

As represented in Fig. 2, the spool I8 may comprise a bushing havingreduced ends upon which are placed the spool ends 28 in the form ofdiscs of spring material, after which the ends of the bushing areriveted over to hold the parts rigidly together.

In the embodiment of my invention shown in Fig. 4, the spool 18a,corresponding to the spool I8 in Fig. 2, is made in a single piece, andis machined directly on the end of the driving shaft 20a. The spool ends28a are not as exlble as the spool ends 28 in Fig. 2, and are formedwith the inner faces 48 sloping radially inwardly, as shown, to receivethe balls 28a. The retainer member Illa, corresponding to the member 28in Fig. 2, is secured at its ends by screws 50 to the U-shape supportingmember Ila, and is positioned so that the balls are held down into rmfrictional engagement with the faces Il. In this connection, theretainer 30a may be siightly resilient to prevent binding of the parts,while at the same time ensuring a good frictional driving 5 engagementbetween the balls, the faces 48 and the disc I2. In this modification,vthe manner of operation is the same as that in Fig. 2. As shown in Fig.l, the disc I2 is the dial plate for indicating the frequency for whichthe ,condenser is l0 tuned in the respective positions thereof.

From the foregoing it will be seen that I have provided an improvedreduction-gear device which is particularly adapted for making fine ad-Justments of a tuning condenser in a radio ref ceiver, which isrelatively simple and reliable in, operation, and which can bemanufactured as a unit and applied to a condenser of standardconstruction.

Although but one embodiment of my inven tion has been shown anddescribed. it will be understood that various modifications thereof,within the Vconception of those skilled in the art, can be made withoutdeparting from the spirit of my invention or the scope of the claims.

I claim as my invention:

i. A reduction-gear device for adjusting electrical tuning apparatusprovided with an actuating member. said device comprising a U-shapesupporting member, a driving member in the 0 form of a spool Journaledin said supporting member for rotation about an axis transverse theretoand provided withend pieces having frictional driving surfaces, a pairof balls disposed between said surfaces on the same side of said axis, aU- shape bali retainer extending across said supporting member from sideto side thereof and provided with openings in which said balls aredisposed and have a free running fit forrotation' about lsubstantiallyparallel axes each substan- 'Q tially perpendicular to the axis ofrotation of said spool, said ball-race having' at least one end thereoffixed to a side of said supporting member, said device being adapted toreceive an edge of said actuating member between said balls wherebyfri'ctional driving engagement is made and maintained between said ballsand the respective opposite faces of said edge and between said ballsannees and said surfaces. and means for rotatingsaid spool.

2. The combination with tuning apparatus having a tuning shaft of adisc-like actuating member fixed on said shaft. a supporting memberfixed to said tuning apparatus. a driving member in the form of a spooljournaled in said supporting member for rotation about an axis parallelto said tuning shaft, said spool having oppositely located frictionaldriving surfaces sloping radially inwardly, a pair of balls disposedbetween said inwardly sloping surfaces, a U-shape ball re tainer fixedto said supporting member and provided with openings in which said ballsare disposed and have a free running fit, the distance between saidinwardly sloping surfaces of said spool being such that upon insertionof said disclike actuating member between `said balls the latter arecaused to make frictional driving engagement with the respectiveopposite faces of said disc, and with the respective opposite ir:-lwardly sloping surfaces of said spool, and means for rotating saidspool.

3. The combination with tuning apparatus having a tuning shaft, of adisc-like actuating member fixed on said shaft, a supporting memberfixed to said tuning apparatuaa drive member supported on saidsupporting member for rotation about an axis substantially parallel tosaid tuning shaft and provided with flexible spaced driving elements ofspring material, lat pair of balls disposed between said exible drivingelements, a U-shape ball retainer fixed to said supporting member andprovided withv openings in the respective opposite arms-of thev U inwhich said balls are disposed for rotation about substantially parallelaxes each substantially perpendicular to the axis of rotation ofV saiddrive member, said drive member being adapted to receive said disc-likeactuating member betweeny saidV balls with a force nt wherebyl saiddriving elements are flexed to maintain a frictional driving engagementbetween said balls and the respective opposite faces ofl said disc, andmeans for rotating said drive member.

DONALD R. DE TAR.

